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Biomedical subjects

S Kale

Publications and source records attributed to S Kale.

16 recordsLinked to original sources
PubMed2000

Bone marrow accessory cells regulate human bone precursor cell development.

OBJECTIVE: Much remains to be learned about the intimate relationship between bone marrow and its surrounding tissue: the bone. We hypothesized that bone marrow accessory cell populations might regulate the development of human bone precursor cells. MATERIALS AND METHODS: We used immunologic phenotyping, and isolation methods to fractionate subpopulations of nonadherent, low-density (NALD) human bone marrow cells. These cells were examined for their ability to support the serum-free survival, proliferation, and expression of bone proteins by highly purified populations of human bone precursor cells. Quantitative assessment of the accessory cell populations as well as human bone precursor cells phenotype was performed using multiparameter flow cytometry. Bone protein expression was evaluated by immunocytochemistry, Western analysis, and enzymatic analysis (for alkaline phosphatase activity). RESULTS: Human bone marrow contains a cell population that stimulates the development of purified bone precursor cells. Feeder-layer studies demonstrate that these osteopoietic accessory cells (OACs) do not require cell-cell interaction to promote bone precursor cell development but, rather, produce soluble molecules responsible for their effects. Flow cytometric analyses reveal that bone marrow derived B cells, T cells, macrophages, natural killer cells, and endothelial cells do not produce this stimulatory factor. The (growth) factor cannot be replaced by addition of exogenous cytokines. The isolation of human transforming growth factor beta receptor type II (TGF-betaRII)-positive cells increases OAC-specific activity in bone cell ex vivo expansion cultures. Moreover, isolation of OAC bone marrow cells characterized by high TGF-betaRII expression, relatively low cellular complexity, and small size yields a population that is highly enriched for OACs. CONCLUSION: We conclude that human bone marrow contains a population of OACs that are an obligate requirement for the early phases of bone cell development ex vivo.

Antigen-Presenting Cells↗
PubMed2000

Three-dimensional cellular development is essential for ex vivo formation of human bone.

Tissue engineering of human bone is a complex process, as the functional development of bone cells requires that regulatory signals be temporally and spatially ordered. The role of three-dimensional cellular interactions is well understood in embryonic osteogenesis, but in vitro correlates are lacking. Here we report that in vitro serum-free transforming growth factor (TGF)-beta1 stimulation of osteogenic cells immediately after passage results in the formation of three-dimensional cellular condensations (bone cell spheroids) within 24 to 48 hours. In turn, bone cell spheroid formation results in the up-regulation of several bone-related proteins (e.g., alkaline phosphatase, type I collagen, osteonectin) during days 3-7, and the concomitant formation of micro-crystalline bone. This system of ex vivo bone formation should provide important information on the physiological, biological and molecular basis of osteogenesis.

Alkaline Phosphatase↗
PubMed2000

Osteopoiesis: the early development of bone cells.

An understanding of the disorders of bone formation clearly requires insights into the complex regulatory events occurring during the evolution of bone precursor cells into osteoblasts. Moreover, a rational approach to therapeutic interventions that might alter the clinical course of bone disorders must take into consideration the exact nature of the developmental control mechanism(s) being affected during the disease process. The process of osteopoiesis involves the proliferation and maturation of primitive precursor cells into functional osteoblasts. The bone cell lineage originates from mesenchymal stem cells that commit to the osteogenic cell lineage becoming osteoprogenitor cells, preosteoblasts, osteoblasts, and osteocytes. In order to understand how different regulatory signals coordinate bone cell development, it is important to study the responses of bone progenitor cells to different microenviromental signals. This requires that lineage markers be identified for the various populations of bone cells and their precursors, that cell separation techniques be established so that cells of the osteogenic lineage can be purified at different stages of differentiation, and that these isolated cells are studied under serum-free, chemically defined conditions. This review focuses on the current understanding of bone progenitor cell development, examining the various types of precursor cells, their responses to cytokines and other extracellular influences, and recent observations on the biochemical and molecular control of lineage-specific gene expression. Although the emphasis is on human cells, the importance of work using rodent cells goes without saying, and is addressed where relevant.

Bone Development↗
PubMed1999

Effect of whole-body vibration on the low back. A study of tractor-driving farmers in north India.

STUDY DESIGN: A retrospective cohort study of tractor-driving farmers (study group) and non-tractor-driving farmers (control group) matched for age, gender, generic/ethnic group, land-holding, and work routines. OBJECTIVES: To determine, using magnetic resonance imaging and clinical investigations, the effect of whole-body vibrations on the back in tractor-driving farmers. SUMMARY OF BACKGROUND DATA: Low back pain and pathologic changes in the lower backs of tractor drivers have been reported. However, no study with a control group matched for work-related risk factors has been reported. METHODS: Fifty tractor-driving farmers were compared with 50 non-tractor-driving farmers matched for age, gender, ethnic group, land-holding, and work routine. Both groups were interviewed for details of work routine, assets held, family profile, and vibration exposure to assess the influence of these parameters on signs and symptoms of backache. Magnetic resonance imaging was done to assess the effect of exposure on whole-body vibration and degenerative changes in the back. Vibration measurements also were done on tractors to observe the actual severity of the vibrations. RESULTS: Regular work-related backache was more common among tractor-driving farmers (40%) than among non-tractor-driving farmers (18%, P = 0.015). Anthropometric evaluation showed abdominal girth and weight to be significantly higher in tractor-driving farmers (P = 0.006 and 0.046, respectively), whereas while height and arm span were similar between the two groups. Clinical examination for evidence of disc or facet degeneration showed no difference between the two groups. Evaluation of magnetic resonance images of tractor-driving farmers and non-tractor-driving farmers by an orthopedic surgeon, radiologist, and neurosurgeon showed degenerative changes to be similar between the two groups (P > 0.050). CONCLUSIONS: Tractor-driving farmers report backache more often than non-tractor-driving farmers, but no significant objective differences on clinical or magnetic resonance imaging evaluation were found between the two groups.

Adult↗
PubMed1996

Urinary tract infection in nephrotic syndrome.

BACKGROUND: The aim was to study the frequency, etiology and predisposing factors of urinary tract infection (UTI) in children with nephrotic syndrome. METHODS: A retrospective analysis of all children with nephrotic syndrome was made to determine the occurrence of infectious complications. RESULTS: UTI was found to be the most common infection (40.26%); 49 episodes of culture-positive UTI were observed in 37 children. All 49 episodes occurred in patients who were initially considered to be steroid nonresponders or in relapse. Fourteen of the 49 episodes (28.6%) were asymptomatic. One child had Grade IV reflux and another had a ureteric calculus. The majority of the children had no underlying urinary tract malformations. The children with UTI had significantly lower serum albumin (P < 0.05) and higher serum cholesterol (P < 0.001) concentrations than the group of 206 children without infections. Non-Escherichia coli organisms accounted for 39% of the culture isolates. CONCLUSIONS: We believe that UTI is an important but often underdiagnosed infection in children with nephrotic syndrome.

Adolescent↗
PubMed1996

LAG2, a gene that determines yeast longevity.

Saccharomyces cerevisiae has a limited life span, measured by the reproductive capacity of the individual cell. Several genes that are differentially expressed during the yeast life span have been isolated. One of these genes, LAG2, has been characterized for its role in longevity. LAG2 is preferentially expressed in young cells. It encodes a predicted 680 amino acid protein with a putative transmembrane helix. The sequences does not show significant similarity to any other DNA or protein sequences in the databases. Deletion of LAG2 in a haploid strain did not affect growth, but it resulted in a 50% decrease in the mean and maximum life span. When LAG2 was overexpressed, the mean and maximum life span of the yeasts was extended by about 36% and 54%, respectively. These results indicate that this is a longevity-assurance gene in yeast.

Amino Acid Sequence↗
PubMed1995

Effect of Beconase nasal spray on olfactory function in post-nasal polypectomy patients: a prospective controlled trial.

Numerous studies have postulated the possible benefit of corticosteroids on olfaction in patients with nasal/sinus disease. Twenty-nine patients with bilateral nasal polyps were included in our study using strict selection criteria to reduce other aetiologies of olfactory dysfunction. The University of Pennsylvania Smell Identification Test (UPSIT) was performed pre-operatively on the right and left nostrils separately. Following intranasal polypectomy the patients received a six-week course of beclomethasone nasal spray (Beconase) to one nostril only, with the other acting as a control. The UPSIT scores were again obtained for each nostril separately. Wilcoxon Signed Rank test revealed no statistically significant difference in UPSIT scores between treated and untreated nostrils (p = 0.31; power 70 per cent; ES = 0.47). We conclude that topical beclomethasone does not improve olfaction following nasal polypectomy.

Administration, Intranasal↗
PubMed1995

Adaptive speckle reduction for improving the differential diagnosis of breast lesions.

Adaptive speckle reduction could mask diagnostic features and adversely affect diagnosis of focal breast lesions. Four radiologists assessed focal breast lesions (29 malignant and 31 benign) by blind review of representative static B-mode scans before and after adaptive speckle reduction processing, scoring 14 diagnostic features for breast cancer and recording their opinions on the diagnosis and on how adaptive speckle reduction affected interpretation of each feature. No adverse affect on diagnosis of malignant (P = 0.756) or benign (P = 1.000) breast lesions was found, despite some differences in scoring of the diagnostic features after adaptive speckle reduction. Observer recognition of most diagnostic features was easier after adaptive speckle reduction (e.g., edge definition [50% of cases], edge regularity [40%], lesion texture [44%], and lesion echogenicity [35%]).

Adult↗
PubMedDate not supplied

Dual role of calmodulin in excitable cells.

Consideration of the enzymatic reactions governing calcium channel phosphorylation and dephosphorylation leads one to deduce that there exist separate groups of enzymes, membrane-bound and cytoplasmic that are activated by a common mediator, calmodulin (CaM), whose time-dependent appearance (via diffusion) at both locales is controlled by both intracellular calcium levels and electrostatic interaction with the membrane. In brief, the change in the sign and extent of the electrical charge borne by the modulator in the presence of calcium (Ca) brings about the electrostatic attraction that enables the transport of [Ca-CaM] to the membrane. This translocation of Ca-CaM makes possible a sequential activation of cellular enzymes whose locations differ. The sequence, both spatial and temporal, of the activation of various cellular enzymes by Ca-CaM appears to be a control network shared in common by excitable cells containing a stimulus-response pathway mediated by second messengers.

Adenylyl Cyclases↗
PubMedDate not supplied

Is McMurray's osteotomy obsolete?

A review of the method of performing, advantages, disadvantages of McMurray's displacement osteotomy with regard to treatment of nonunion of transcervical fracture neck femur with viable femoral head was carried out in this study of ten cases, in view of the abandonment of the procedure in favour of angulation osteotomy. Good results obtained in the series attest to the usefulness of McMurray's osteotomy in the difficult problem of nonunion of transcervical fracture neck femur in well selected cases with certain advantages over the angulation osteotomy due to the 'Armchair effect'.

Adult↗
PubMedDate not supplied

Serous fluid leakage following modified Blalock-Taussig operation using PTFE grafts.

BACKGROUND: Serous fluid leakage is an unusual but often devastating complication following the placement of a modified Blalock-Taussig shunt using a polytetrafluoroethylene graft. METHOD AND RESULTS: Between September 1994 and September 1999, out of 268 patients undergoing a modified Blalock-Taussig shunt using polytetrafluoroethylene grafts, 10 developed massive pleural effusion or seroma due to a leak from the surface of the shunt. The age of the patients ranged from 9 days to 7 years. There were 7 males and 3 females. Nine patients presented with respiratory distress between 2 and 12 weeks of shunt surgery and one presented with sudden cardiac arrest. The shunt was patent in all the patients. Initial management was conservative. i.e. by pharmacological means and tube thoracostomy. Reoperation was undertaken in 9 patients when conservative treatment failed. All patients survived except one who had a cardiac arrest before any intervention could be carried out. CONCLUSIONS: Patients with serous effusion have significant morbidity and mortality and often require reoperation. The initial management remains conservative but, if unsuccessful, re-exploration can be undertaken as it proved to be uniformly successful in our experience.

Child↗